1. Field of the Invention
This invention relates to a solar cell module using a two-side incidence type solar cell capable of generating power by utilizing light incident from both front and rear surfaces.
2. Description of Prior Art
A conventional solar cell module comprises a plurality of solar cells 101 including a transparent front surface member 102, a rear surface member 103, and a transparent sealing material 104 sealed between the front surface member 102 and the rear surface member 103 as shown in a schematic cross sectional view of FIG. 10. Each of the solar cells 101 is electrically connected in series or in parallel each other with a conductive connecting member (not shown), and an output electricity is taken out from the module.
Glass is suitable for the front surface member 102. Particularly a reinforced glass having excellent light transmittivity and shock resistance is generally used. The rear surface member 103 comprises a metal film of aluminum or the like sandwiched between weather resistant resin films of PET (polyethylene terephthalate) or the like so as to be weather and moisture proof and electrically insulative. PVB (polyvinyl butyral) capable of suppressing degradation of light transmittivity caused by ultra violet rays and EVA (ethylene vinyl acetate) having excellent moisture proofness is mainly used as the sealing material 104.
A frame 105 of aluminum may be mounted around the module so as to improve the strength of the whole module.
It is preferred to increase an area ratio of the solar cells to the solar cell module in order to increase quantity of power generation in the conventional solar cell module. Thus, as shown in a schematic plan view of FIG. 11, solar cells having an approximately square shape are arrayed in matrix with little spaces of approximately 2-5 mm.
Meantime, it was found that power is generated not only by light incident from a front surface side of the solar cells but by light incident from a rear surface side of the solar cells, and the two-side incidence type solar cell capable of generating power by utilizing light incident from both of the front and rear surfaces has been developed.
A solar power generation system using the two-side incidence type solar cells is provided with solar cell modules -arranged on the ground or on a roof and comprising the two-side incidence type solar cells arrayed in matrix with little spaces to be close with each other. Scattered light which is incident to a lower side of the solar cell module and is irregularly reflected on the ground or a roof is incident to the rear surface side of the two-side incidence type solar cell.
In the above solar cell module, reflected light from a part shaded by a roof or from a ground is weak or less, and light is not incident from the shaded part to a rear surface of the two-side incidence type solar cell. Therefore, power generation efficiency per solar cell is not improved than expected, and reduction of cost by reducing the number of solar cells and reduction of weight of the solar cell module are not achieved.
This invention was made to provide a solar cell module having excellent output characteristics and manufactured at low cost without ineffectiveness as described above.
In order to solve the existing problems, the solar cell module according to this invention comprises a front surface member which is transparent, a rear surface member, a plurality of two-side incidence type solar cells arranged between the front surface member and the rear surface member, a connecting member which is conductive for electrically connecting the solar cells in series or in parallel, and a reflecting surface for reflecting light incident from the front surface member to a space between the solar cells which are adjacent each other and introducing reflected light to a rear surface of the solar cell.
In this solar cell module, incident light entered from a front surface member to a space between adjacent solar cells is reflected on the reflecting surface, and the reflected light reflected on the reflecting surface is introduced to the rear surface of the solar cell. Therefore, both of the incident light and the reflected light is incident to the solar cell, and power generation per solar cell increases as compared with the conventional solar all module of utilizing only incident light. Therefore, this invention can provide a solar cell module capable of reducing the number of solar cells necessary for obtaining same power generation as that in the existing solar cell module, having excellent output characteristics, and manufactured at low cost.
The reflecting surface is a scattering reflecting surface and is provided at least in a position corresponding to the space. Or, the reflecting surface is formed to be a recessed surface corresponding to the solar cell.
As described above, when the reflecting surface is the scattering reflecting surface, the incident light can be reflected slantly from the reflecting surface. Thus, the reflected light can be introduced to the rear surface of the solar cell effectively in spite of changes of an incident angle of the sunlight with time.
A ratio of areas of the solar cells to an area of the solar cell module is approximately 0.4-0.9. And, the solar cell has an approximately circle shape. With this structure, a solar cell module capable of generating greater power per module can be provided.
The reflecting surface is provided on a solar cell side of the rear surface member or on a rear surface side of the rear surface member.